From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 17411 invoked by alias); 2 May 2014 16:14:51 -0000 Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-bugs-owner@gcc.gnu.org Received: (qmail 17381 invoked by uid 48); 2 May 2014 16:14:47 -0000 From: "ktietz at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug rtl-optimization/59429] Missed optimization opportunity in qsort-style comparison functions Date: Fri, 02 May 2014 16:14:00 -0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: rtl-optimization X-Bugzilla-Version: 4.8.1 X-Bugzilla-Keywords: X-Bugzilla-Severity: minor X-Bugzilla-Who: ktietz at gcc dot gnu.org X-Bugzilla-Status: NEW X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-SW-Source: 2014-05/txt/msg00083.txt.bz2 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59429 --- Comment #9 from Kai Tietz --- The general solution here for patterns like '(a cmp1 b ? x : (a cmp2 b ? y : z))' would be to split such statment up into 3 conditions like: if (a cmp1 b) r = x; else if (a cmp2 b) r = y; else if (!(a cmp2 b && a cmp1 b)) r = z; By this we can resort conditions and try to normalize it. Of course this just works for floating-points with fast-math, or just on integral types.